Enhance error messages returned from the HTTP requests

I can find that many places of the LRA code returns simple HTTP status code without any further information. With that it's hard to understand reasons for the failure.

It would be good, in my opinion, to have the error message part of the message body.
That's done at some places in the code but other places do not contain such handling.

The idea of this enhancement would be to provide the error message for thrown exception and for the response message as well.